High lift systems of this type are often designed such that in the extended position of the flap a gap between a regulating flap of the high lift system and the main wing is formed. For improving the lift, the gap is defined such that, under certain flight conditions, a defined quantity of air can pass through this gap from the lower face of the high lift system onto the upper face of the high lift system, in particular of the regulating flap. The gap geometry ensures a lift state as a function of the aerodynamic geometry of the whole high lift system. In the retracted state, no gap is present, and as a result it is not possible to supply the flow above the high lift system with a flow of air from the lower face of the high lift system.